Vitamin D Status in Relation to Glucose Metabolism and Type 2 Diabetes in Septuagenarians

OBJECTIVE: Vitamin D deficiency is thought to be a risk factor for development of type 2 diabetes, and elderly subjects at northern latitudes may therefore be at particular risk. RESEARCH DESIGN AND METHODS: Vitamin D status was assessed from serum concentrations of 25-hydroxyvitamin D(3) [25(OH)D(3)] in 668 Faroese residents aged 70–74 years (64% of eligible population). We determined type 2 diabetes prevalence from past medical histories, fasting plasma concentrations of glucose, and/or glycosylated hemoglobin (HbA(1c)). RESULTS: We observed 70 (11%) new type 2 diabetic subjects, whereas 88 (13%) were previously diagnosed. Having vitamin D status <50 nmol/L doubled the risk of newly diagnosed type 2 diabetes after adjustment for BMI, sex, exposure to polychlorinated biphenyls, serum triacylglyceride concentration, serum HDL concentration, smoking status, and month of blood sampling. Furthermore, the HbA(1c) concentration decreased at higher serum 25(OH)D(3) concentrations independent of covariates. CONCLUSIONS: In elderly subjects, vitamin D sufficiency may provide protection against type 2 diabetes. Because the study is cross-sectional, intervention studies are needed to elucidate whether vitamin D could be used to prevent development of type 2 diabetes.